4.4 bln-year-old crystals confirms theory of 'cool early Earth'

A new study has revealed data that confirms the Earth's crust first formed at least 4.4 billion years ago, just 160 million years after the formation of our solar system.

The work by an international team of researchers led by University of Wisconsin-Madison geoscience Professor John Valley showed that the time when our planet was a fiery ball covered in a magma ocean came earlier.

"This confirms our view of how the Earth cooled and became habitable. This may also help us understand how other habitable planets would form," Valley said.

The new study confirms that zircon crystals from Western Australia's Jack Hills region crystallized 4.4 billion years ago, building on earlier studies that used lead isotopes to date the Australian zircons and identify them as the oldest bits of the Earth's crust.

The microscopic zircon crystal used by Valley and his group in the current study is now confirmed to be the oldest known material of any kind formed on Earth.

The study, according to Valley, strengthens the theory of a "cool early Earth," where temperatures were low enough for liquid water, oceans and a hydrosphere not long after the planet's crust congealed from a sea of molten rock.